Pyrophosphoric acid

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  • Identifiers

    CAS number
    2466-09-3

    Molecular formula
    H4O7P2

    SMILES
    OP(=O)(O)OP(=O)(O)O

    Safety labels

    Corrosive
    Corrosive

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Odorless 73.52%
    Clean 17.14%
    Sour 16.31%
    Green 14.55%
    Fresh 14.05%
    Sulfurous 13.62%
    Sharp 13.28%
    Pungent 12.93%
    Ethereal 12.24%
    Alcoholic 12.0%

     

    Flavor
    Odorless 64.69%
    Sour 36.84%
    Vinegar 26.03%
    Pungent 22.49%
    Mild 21.51%
    Bland 21.33%
    Formyl 20.08%
    Sharp 19.99%
    Yeast 19.83%
    Soy 19.55%

     

    Odor impact est.
    Low

  • Properties

    XLogP3-AA
    -3.2

    pKa est.
    4.47 (weak acid)

    Molecular weight
    177.98 g/mol

    Melting point expt.

    • 61 °C

    Flash point

    • 276.28 ˚C est.

  • Synonyms

    • Diphosphoric acid
    • Pyrophosphoric acid
    • 2466-09-3
    • phosphono dihydrogen phosphate
    • (phosphonooxy)phosphonic acid
    • 4E862E7GRQ
    • H4P2O7
    • CHEBI:29888
    • DTXSID4075035
    • RefChem:55955
    • DTXCID4037118
    • 219-574-0
    • hydron;phosphonato phosphate
    • Diphosphorsaeure
    • Phosphonooxyphosphonic acid
    • Pyrophosphoric Acid (Technical Grade)
    • 33943-49-6
    • PPV
    • Pyrophosphorsaeure
    • acide diphosphorique
    • pyrophosphate TMS4
    • EINECS 219-574-0
    • DIPHOSPHORIC-ACID
    • DIPHSOPHORIC ACID
    • (P2O74-)Diphosphate
    • (4-)Diphosphoric acid ion
    • Oxy-1,1-diphosphonic acid
    • SCHEMBL3654
    • NCIStruc1_000506
    • NCIStruc2_000426
    • UNII-4E862E7GRQ
    • GTPL3151
    • SCHEMBL1573170
    • CHEMBL1160571
    • PYROPHOSPHORIC ACID [MI]
    • CHEBI:233648
    • MSKW100132
    • NCI56751
    • Pyrophosphoric acid, technical grade
    • BDBM50147591
    • CCG-37688
    • NCGC00013687
    • NSC289196
    • PYROPHOSPHORIC ACID [WHO-DD]
    • AKOS015856732
    • [(HO)2P(O)OP(O)(OH)2]
    • DB04160
    • NSC-289196
    • mu-oxido-bis(dihydroxidooxidophosphorus)
    • NCGC00013687-02
    • NCGC00013687-03
    • NCGC00096798-01
    • BP-14180
    • NCI60_004388
    • CS-0030756
    • NS00013536
    • C00013
    • P00025
    • Pyrophosphoric acid, SAJ first grade, >=90.0%
    • L000488
    • Q411092
    • Pyrophosphoric acid, Vetec(TM) reagent grade, 94%
    • 2CB62164-1ACF-40BE-BF6A-880D0A00850A
    • 1,5-dihydrido-2,4-dihydroxido-2,4-dioxido-1,3,5-trioxy-2,4-diphosphy-[5]catena
    • 2466-09-3

  • Applications

    Pyrophosphoric acid (H4P2O7, CAS 2466-09-3) is primarily used as an intermediate for the synthesis of phosphate esters and polyphosphates; it also functions as a dehydrating agent and acid catalyst in organic synthesis (esterification and condensation reactions). It serves as a precursor to pyrophosphate salts that act as sequestrants, scale inhibitors, and processing aids in detergents, water-treatment formulations, and cleaning products. In coatings, inks and polymer formulations, it provides phosphate-containing species for surface modification, crosslinking and stabilization of films. It is typically handled as a reactive reagent in industrial manufacturing and surface-treatment processes under appropriate regulatory controls.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 125.04
    methanol 201.66
    isopropanol 96.44
    water 306.77
    ethyl acetate 31.47
    n-propanol 74.83
    acetone 119.41
    n-butanol 59.82
    acetonitrile 33.35
    DMF 425.93
    toluene 9.12
    isobutanol 42.33
    1,4-dioxane 50.04
    methyl acetate 29.81
    THF 213.03
    2-butanone 50.36
    n-pentanol 33.88
    sec-butanol 50.8
    n-hexane 4.08
    ethylene glycol 165.26
    NMP 234.49
    cyclohexane 3.62
    DMSO 617.27
    n-butyl acetate 23.79
    n-octanol 17.42
    chloroform 7.15
    n-propyl acetate 23.06
    acetic acid 66.59
    dichloromethane 11.08
    cyclohexanone 45.16
    propylene glycol 147.75
    isopropyl acetate 29.21
    DMAc 210.81
    2-ethoxyethanol 130.96
    isopentanol 37.37
    n-heptane 5.56
    ethyl formate 41.85
    1,2-dichloroethane 14.95
    n-hexanol 34.4
    2-methoxyethanol 310.35
    isobutyl acetate 9.72
    tetrachloromethane 3.23
    n-pentyl acetate 17.98
    transcutol 112.45
    n-heptanol 21.2
    ethylbenzene 4.08
    MIBK 39.73
    2-propoxyethanol 161.91
    tert-butanol 88.04
    MTBE 24.26
    2-butoxyethanol 68.23
    propionic acid 49.61
    o-xylene 8.98
    formic acid 133.23
    diethyl ether 40.93
    m-xylene 11.32
    p-xylene 4.3
    chlorobenzene 3.7
    dimethyl carbonate 54.58
    n-octane 2.26
    formamide 232.89
    cyclopentanone 118.84
    2-pentanone 66.11
    anisole 13.41
    cyclopentyl methyl ether 65.26
    gamma-butyrolactone 122.25
    1-methoxy-2-propanol 287.7
    pyridine 23.82
    3-pentanone 38.62
    furfural 87.88
    n-dodecane 1.46
    diethylene glycol 197.76
    diisopropyl ether 14.7
    tert-amyl alcohol 46.63
    acetylacetone 70.06
    n-hexadecane 1.58
    acetophenone 17.96
    methyl propionate 52.56
    isopentyl acetate 15.05
    trichloroethylene 11.79
    n-nonanol 16.37
    cyclohexanol 31.68
    benzyl alcohol 20.98
    2-ethylhexanol 14.03
    isooctanol 13.54
    dipropyl ether 32.14
    1,2-dichlorobenzene 3.66
    ethyl lactate 44.23
    propylene carbonate 47.1
    n-methylformamide 204.03
    2-pentanol 47.64
    n-pentane 7.0
    1-propoxy-2-propanol 115.55
    1-methoxy-2-propyl acetate 53.34
    2-(2-methoxypropoxy) propanol 52.18
    mesitylene 9.11
    ε-caprolactone 39.06
    p-cymene 4.96
    epichlorohydrin 72.77
    1,1,1-trichloroethane 6.51
    2-aminoethanol 173.65
    morpholine-4-carbaldehyde 168.76
    sulfolane 219.57
    2,2,4-trimethylpentane 2.06
    2-methyltetrahydrofuran 63.19
    n-hexyl acetate 19.0
    isooctane 2.3
    2-(2-butoxyethoxy)ethanol 71.0
    sec-butyl acetate 13.86
    tert-butyl acetate 34.19
    decalin 1.6
    glycerin 254.18
    diglyme 98.86
    acrylic acid 52.32
    isopropyl myristate 10.58
    n-butyric acid 52.56
    acetyl acetate 16.04
    di(2-ethylhexyl) phthalate 9.62
    ethyl propionate 27.29
    nitromethane 108.22
    1,2-diethoxyethane 27.87
    benzonitrile 10.3
    trioctyl phosphate 11.71
    1-bromopropane 9.64
    gamma-valerolactone 139.97
    n-decanol 13.0
    triethyl phosphate 14.31
    4-methyl-2-pentanol 25.07
    propionitrile 25.24
    vinylene carbonate 31.3
    1,1,2-trichlorotrifluoroethane 73.75
    DMS 16.75
    cumene 3.7
    2-octanol 14.27
    2-hexanone 26.66
    octyl acetate 13.42
    limonene 7.17
    1,2-dimethoxyethane 117.32
    ethyl orthosilicate 13.36
    tributyl phosphate 11.58
    diacetone alcohol 88.98
    N,N-dimethylaniline 16.65
    acrylonitrile 33.72
    aniline 24.06
    1,3-propanediol 148.73
    bromobenzene 2.44
    dibromomethane 7.76
    1,1,2,2-tetrachloroethane 14.37
    2-methyl-cyclohexyl acetate 12.82
    tetrabutyl urea 21.04
    diisobutyl methanol 12.23
    2-phenylethanol 21.84
    styrene 3.7
    dioctyl adipate 13.88
    dimethyl sulfate 115.72
    ethyl butyrate 22.94
    methyl lactate 113.69
    butyl lactate 32.75
    diethyl carbonate 13.55
    propanediol butyl ether 70.24
    triethyl orthoformate 19.54
    p-tert-butyltoluene 6.28
    methyl 4-tert-butylbenzoate 30.32
    morpholine 91.26
    tert-butylamine 42.61
    n-dodecanol 9.9
    dimethoxymethane 237.69
    ethylene carbonate 29.93
    cyrene 65.94
    2-ethoxyethyl acetate 23.95
    2-ethylhexyl acetate 10.94
    1,2,4-trichlorobenzene 4.36
    4-methylpyridine 23.24
    dibutyl ether 11.07
    2,6-dimethyl-4-heptanol 12.23
    DEF 80.25
    dimethyl isosorbide 79.89
    tetrachloroethylene 10.13
    eugenol 42.72
    triacetin 21.42
    span 80 42.12
    1,4-butanediol 59.96
    1,1-dichloroethane 9.96
    2-methyl-1-pentanol 18.12
    methyl formate 124.94
    2-methyl-1-butanol 32.53
    n-decane 2.27
    butyronitrile 27.0
    3,7-dimethyl-1-octanol 11.43
    1-chlorooctane 5.23
    1-chlorotetradecane 2.81
    n-nonane 2.31
    undecane 1.8
    tert-butylcyclohexane 1.73
    cyclooctane 2.68
    cyclopentanol 67.8
    tetrahydropyran 34.15
    tert-amyl methyl ether 25.61
    2,5,8-trioxanonane 78.03
    1-hexene 7.56
    2-isopropoxyethanol 70.86
    2,2,2-trifluoroethanol 60.82
    methyl butyrate 31.44

    Scent© AI

1 4

IFRA standard 51

Recommendation
No restriction
Maximum acceptable concentrations in the finished product (%)
Category 1
Products applied to the lips
 No restriction Category 7A
Rinse-off products applied to the hair with some hand contact
 No restriction
Category 2
Products applied to the axillae
 No restriction Category 7B
Leave-on products applied to the hair with some hand contact
 No restriction
Category 3
Products applied to the face/body using fingertips
 No restriction Category 8
Products with significant anogenital exposure
 No restriction
Category 4
Products related to fine fragrance
 No restriction Category 9
Products with body and hand exposure, primarily rinse off
 No restriction
Category 5A
Body lotion products applied to the body using the hands (palms), primarily leave on
 No restriction Category 10A
Household care products with mostly hand contact
 No restriction
Category 5B
Face moisturizer products applied to the face using the hands (palms), primarily leave on
 No restriction Category 10B
Household care products with mostly hand contact, including aerosol/spray products (with potential leave-on skin contact)
 No restriction
Category 5C
Hand cream products applied to the hands using the hands (palms), primarily leave on
 No restriction Category 11A
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate without UV exposure
 No restriction
Category 5D
Baby Creams, baby Oils and baby talc
 No restriction Category 11B
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate with potential UV exposure
 No restriction
Category 6
Products with oral and lip exposure
 No restriction Category 12
Products not intended for direct skin contact, minimal or insignificant transfer to skin
 No restriction